An electronic fuse, also known as an “e-fuse,” includes a transistor switching element and a current sensing resistor that are both placed in the path of a supply current. The electronic fuse also includes a controller that is configured to turn on the switching element to supply current along the path and to turn off the switching element if the supplied current exceeds a predetermined threshold.
In some electronic systems it is necessary to supply current to a load using more than one high-power path. A rack-mounted server computer system provides one example of this. In such a server system, it is common to provide power to a motherboard through sockets that connect the motherboard to a backplane. Current from a single power supply is routed to the motherboard through the backplane via the sockets. If a single socket assembly were used for this purpose, the socket assembly would have to be robust enough to handle the entire maximum rated current requirement of the motherboard load. But such a socket would be bulky and expensive. Instead, two separate sockets are sometimes used instead of one. In this arrangement, the current supplied to the load is distributed such that there are two high-power paths, one through each socket. Smaller and less expensive sockets may be used in this case because the amount of current passing through each socket is lower than the total current drawn by the load.
In any such arrangement it is usually necessary to employ an electronic fuse to limit the current being supplied to the load—such as to the motherboard load in the case of the server computer system. In architectures that use more than one high-power path, however, a design challenge arises regarding where to place the electronic fuse.